In a Sept. 22 editorial, The Post lauded Nicaragua's move to open La Prensa, but echoed the administration's empty charges that Nicaragua will not comply with the peace accord. Ironically, the day the editorial appeared, Nicaragua continued with its series of steps (not a ''single step,'' as the editorial said) by calling for a unilateral cease-fire and reopening the Catholic radio.

The Sandinista government is already more open than the administration and the press portray it. For example, the editorial stated that the Sandinistas "have rewritten their country's basic law, for instance, to subordinate the nation's army and security forces to their party alone.'' This is plainly false. Nicaragua's new constitution states clearly in Article 95: ''The Sandinista Popular Army has a national character and must protect, respect and obey this political Constitution.''

When the National Assembly debated the constitution and the issue of the army, the title ''Sandinista Popular Army'' was agreed to, even by the opposition. Conservative assembly delegate Clemente Guido said at the time that he had no objection to the name ''Sandinista'' in the title, in honor of Augusto Cesar Sandino. In the end, it was agreed that the army was under national control and that the ''Sandinista'' in the title referred to Mr. Sandino and not the Sandinistas' party. (The Democratic Conservatives, Popular Social Christians, Socialists and Sandinista delegates approved the wording. The Independent Liberals, Communists and Marxist-Leninist representatives voted down the final wording.)

Given the steps Nicaragua has taken to comply with the peace accord since it was signed Aug. 7, I would suggest that The Post monitor and inform its readers about El Salvador, Guatemala and Honduras -- whose compliance with the same peace accord has been less rigorous and practically ignored.

BETSY COHN Director, Central American Historical Institute Intercultural Center, Georgetown University Washington